# Questions tagged [parton]

A parton is a gluon, quark or antiquark in the eponymous model of scattering involving hadrons. In the hadron's infinite-momentum frame, incoming particles will be scattered instantaneously and incoherently, reducing the problem to a simple kernel convolved with parton distributions, at a particular physical scale (as probed by the inverse of the momentum transfer).

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### How to derive operator form of the parton distribution function

A similar question is found here in Stackexchange a year ago without any response. I am following the formulation of the parton densities from the handbag diagram in Collins Handbook of Perturbative ...
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### Computing hadronic cross sections with PDFs

I am trying to estimate the cross section for a BSM process at the LHC, and I would like to ask if anyone knows what is the simplest way to integrate over the PDFs, for example with Mathematica. I ...
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### Parton model and impulse approximation for the process $2\to 1$

Consider a process $$\tag 1 N+N\to X+\text{all},$$ where $N$ are nucleons and $X$ is some massive particle. Assuming the parton model is valid and there is vertex $PP'X$, where $P,P'$ are partons ...
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### Applicability of parton model at low factorization scale

Consider scattering process at partonic level occuring at low factorization scale $\mu^{2}\lesssim 1\text{ GeV}^{2}$ (for example, with the "hard" process $2\to 1$ with low mass produced particle, ...
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### Shape of partons from differential cross section as function of $Q^2$: is it valid, despite the $\theta$ dependence?

For deep inelastic scattering of electron on a nucleon the following graph represent the ratio $$\frac{\frac{d^2 \sigma}{d \Omega d E'}}{(\frac{d \sigma}{d \Omega})|_{Mott}}$$ as a function of $Q^2$,...
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Consider deep inelastic scattering of electron on proton and parton model: $F_2(x)$ as a function of Bjorken $x$ at fixed $Q^2$ goes as in the following graph. The differential cross section is: $$\... 1answer 52 views ### Deep Inelastic Scattering cross section: Smearing of the F_2(x) graph and relation of form factors with Fourier Trasform of nucleon distibutions Consider Deep Inelastic Scattering cross section$$\frac{d^2 \sigma}{d \Omega d \nu}=(\frac{d \sigma}{d \Omega})|_{Mott} \{ W_2(Q^2,\nu)+2 W_1(Q^2,\nu) \tan^2(\theta/2) \}$$It is said that the ... 1answer 53 views ### Drell-Yan process and factorization scale What is the most relevant choice for the factorization scale of the Drell-Yan process? Can it be the invariant mass at the reaction threshold? 1answer 22 views ### Computing the p_{T} spectrum of hadrons in pp collisions by knowing the p_{T} spectrum of quarks Consider the differential quark production cross-section d\sigma_{pp \to q\bar{q}}/d|\mathbf{p}_{T}|, where |\mathbf p_{T}| is the momentum transverse to the pp beam line. Next, assume that the ... 0answers 103 views ### Bjorken Scaling and the Parton Model It is often said that Bjorken scaling of the deep inelastic structure functions $$\nu W_2(\nu ,Q^2)\rightarrow F(x)$$ (where Q^2 is the virtuality of the photon, \nu=\... 1answer 71 views ### Parton distribution function and factorization scale Consider some deep inelastic scattering y f\to y f, where f is a parton inside a nucleon N, and y is some particle. The cross-section is then$$ \sigma_{\text{DIS}} = \int dx f_{N/f}(x,Q^{2})\...
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Consider the leading-order (LO) DGLAP ((Dokshitzer–Gribov–Lipatov–Altarelli–Parisi) equation x \mu^2 \frac{d xg(x,\mu^2)}{d\mu^2}= \alpha_s \int_x^1 dz P_{gg}(z) \frac{x}{z} g(\frac{x}{z}, \mu^2) + \...
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### Parton model in experimental particle physics

In experimental particle physics, what does "parton-level" , "particle-level" and "detector-level" exactly mean ? PS : detailed explanations, links, etc .. would be deeply appreciated
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### Parton distribution function - dependence on $Q$?

In one of my previous questions I define the parton distribution function, following that of D.Stump as follows: $f_i(x,Q^2)dx$ is the mean number of the $i$th type of patron with longitudinal ...
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### Do electrons interact with gluons?

I know the straightforward answer to this question is no: electrons are leptons which by definition don't interact via the strong force, gluons are the mediators of the strong force and hence ...
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### Sea quark parton annihilation?

Consider the figure below1: This can be read as follows (please correct me if I am wrong): two particles come in and 'fragment', a parton from each particle $C$ and $D$ annihilate to form the ...
In Schwartz's book, 'Quantum Field Theory and the Standard Model' P.$696$, he starts to derive an expression for a parton distribution function in terms of matrix elements evaluated on the lightcone. ...